102 ANNUAL OF SCIENTIFIC DISCOVERY. 



confined to our earth, but is common to other, and probably to all, 

 the bodies of our system ; and, from analogy, we may also infer that 

 electricity, a coordinate if not an identical principle, is also cosmicul 

 in its presence and the extent of its operation. That the earth is 

 negatively electrified was proved by Volta at the close of the last 

 century. For this purpose he received the spray from a cascade on 

 the balls of a sensitive electrometer ; the leaves diverged with neg- 

 ative electricity. 



This experiment has been repeated in various parts of the globe, 

 and always with the same result. That it indicates the negative con- 

 dition of the earth, is evident when we reflect that the upper level 

 from which the water falls must be considered as the exterior of the 

 charged globe, and hence must be more intensely electrified than 

 points nearer the centre. Since the earth is, as a whole, a good con- 

 ductor of electricity, as shown by the operations of the telegraph, the 

 electrical tension of it cannot differ much in different parts, and we 

 are at present unacquainted with any chemical, thermal, or mechan- 

 ical action on land of sufficient magnitude to produce this constant 

 electrical state. We are therefore induced to adopt the conclusion 

 that the earth, in relation to space around it, is permanently electri- 

 cal ; that perhaps the ethereal medium, which has been assumed as 

 the basis of electricity, as was supposed by Newton, becomes rarer in 

 the vicinity and within bodies of ponderable matter. Be this as it 

 may, all the phenomena observed in the atmosphere, and which have 

 so long perplexed the physicist, can be reduced apparently to order, 

 and their dependences and associations readily understood, in accord- 

 ance with the foregoing assumption. This is not a mere vague sup- 

 position, serving to explain in a loose way certain phenomena, but one 

 which enables us not only to group at once a large class of facts which 

 from any other point of view would appear to have no connection 

 with each other, but also to devise means for estimating the relative 

 intensity of action, and to predict, both in mode and measure, changes 

 of atmospheric electricity before they occur. It follows, as a logical 

 consequence from this theory, that salient points, such as the tops of 

 mountains, trees, spires, and even vapors, if of conducting materials, 

 will be more highly excited than the general surface of the globe, in 

 a manner precisely similar to the more intense excitement of elec- 

 tricity at the summit of a point projecting from the surface of the 

 prime conductor of an ordinary electrical machine. 



It also follows, from the same principle, that if a long metallic con- 

 ductor be insulated in the atmosphere, its lower end, next the earth, 

 will be positive, and the upper end negative. The natural electricity 

 will be drawn down by the unsaturated matter of the earth into 

 the lower end of the wire, which will thence become redundant, while 

 the upper end will be rendered negative, or under-saturated. That 

 this condition really takes place in the atmosphere was proved in a 

 striking manner by the experiment of Guy Lussac and Biot, in their 

 celebrated aerial voyage, which consisted in lowering from the balloon 

 an insulated copper wire, terminated at each end by a small ball. 

 The upper end of this was found to be negative, and consequently 

 the lower end must have been positive, since the whole apparatus, 

 including the balloon, was insulated. The experiments should be re- 



